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JAMA Surg. Author manuscript; available in PMC 2016 December 01. Published in final edited form as: JAMA Surg. 2015 December 1; 150(12): 1134–1140. doi:10.1001/jamasurg.2015.2606.
Effect of Delirium and Other Major Complications After Elective Surgery in Older Adults Lauren J. Gleason, MD1,2, Eva M. Schmitt, PhD2, Cyrus M. Kosar, MA2, Patricia Tabloski, PhD3, Jane S. Saczynski, PhD4, Thomas Robinson, MD5, Zara Cooper, MD6, Selwyn O. Rogers Jr., MD, MPH7, Richard N. Jones, ScD8, Edward R. Marcantonio, MD, SM1,*, and Sharon K. Inouye, MD, MPH1,2,*
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1Department
of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School,
Boston, MA 2Aging
Brain Center, Institute for Aging Research, Hebrew SeniorLife
3William
F. Connell School of Nursing, Boston College, Boston, MA
4Division
of Geriatric Medicine and Meyers Primary Care Institute, University of Massachusetts Medical School, Worcester, MA
5Department
of Surgery, University of Colorado
6Department
of Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
7University
of Texas Medical Branch at Galveston, Galveston, Texas
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8Departments
of Psychiatry and Human Behavior, Brown University Warren Alpert Medical School, Providence RI
Abstract Importance—Major postoperative complications and delirium contribute independently to adverse outcomes and high resource utilization in patients undergoing major surgery; however, their inter-relationship is not well-examined. Objective—To evaluate the association of major postoperative complications and delirium, alone and in combination, with adverse outcomes after surgery. Design—Prospective cohort study.
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Setting—Two large academic medical centers. Participants—Patients without recognized dementia or history of delirium, age 70 and older who underwent elective major orthopedic, vascular, and abdominal surgeries with a minimum 3day hospitalization.
Corresponding Author: Sharon K. Inouye, MD, MPH, Aging Brain Center, Institute for Aging Research, Hebrew SeniorLife; 1200 Centre Street; Boston, MA 02131 USA, [email protected], Phone: 617-971-5390; Fax: 617-971-5309. *Drs. Marcantonio and Inouye contributed equally as co-senior authors. Drs. Gleason and Inouye had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
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Main Outcome and Measures—Major postoperative complications, defined as life altering or threatening events (Accordion Severity ≥ grade 2), were identified by expert panel adjudication. Delirium was measured daily with the Confusion Assessment Method and a validated chart review method. Four subgroups were analyzed: (1) no complications, no delirium; (2) complications alone; (3) delirium alone; and (4) both complications and delirium. Adverse outcomes included length of stay (LOS) > 5 days, institutional discharge, and rehospitalization within 30 days of discharge.
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Results—Of 566 participants, mean age (±SD) was 76.7± 5.2 years, 42% male and 92% white. Forty-seven (8%) developed major complications, and 135 (24%) developed delirium. When compared to no complications, no delirium as the reference group, major complications alone contributed only to prolonged LOS (RR 2.8, 95% CI 1.9–4.0); by contrast, delirium alone significantly increased all adverse outcomes, including prolonged LOS (RR 1.9, 95% CI 1.4–2.7), institutional discharge (RR 1.5, 95% CI 1.3–1.7), and 30-day readmission (RR 2.3, 95% CI 1.4– 3.7). The subgroup with both complications and delirium had the highest rates of all adverse outcomes, including prolonged LOS (RR 3.4, 95% CI 2.3–4.8), institutional discharge (RR 1.8, 95% CI 1.4–2.5) and 30-day readmission (RR 3.0, 95% CI 1.3–6.8). Delirium exerted the highest attributable risk at a population level (5.8%, 95% CI 4.7–6.8) compared with all other adverse events (prolonged LOS, institutional discharge, or readmission). Conclusions and Relevance—Major postoperative complications and delirium are separately associated with adverse events and demonstrate a strong combined effect. Delirium occurs more frequently, and has greater impact at the population level than other major complications. Keywords Delirium; postoperative complications; Confusion Assessment Method; adverse surgical outcomes
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Introduction Thirty-six percent of inpatient operations were performed in patients ≥65 years old.1 The number of patients is projected to increase as the population ages.1,2 Understanding the risks for adverse outcomes in the aging surgical population is essential to implement programs with the potential to decrease morbidity, mortality, costs, and safety. Postoperative complications increase with advancing age.3,4 These complications, occurring in 10–25% older persons,3–7 can lead to adverse outcomes such as disability, loss of independence, diminished quality of life, high health care costs, and increased mortality.8 Physiologic changes across organ systems, cardiovascular, neurological, and pulmonary systems, contribute to the increasing risk of postoperative complications with advancing age.6,8
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Postoperative delirium as the leading complication of major surgery in older persons with adverse consequences has been well documented across many studies.9–12 It is associated with higher in-hospital and 6-month mortality, functional decline, greater rates of institutional discharge, longer lengths of stay (LOS), increased use of hospital resources and higher healthcare costs.9–14 Delirium rates following surgery range from 5%–50%.12,14,15 Its impact on annual health care costs is estimated at over $182 billion per year in the U.S. (2011 USD),16 and thus, has assumed increasing attention as a public health and patient
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safety priority.17 Since complications and delirium are often preventable, they can be tracked and monitored as markers of quality of care.18 Such markers have become a major focus of the National Quality Forum and emerged at the forefront of many quality improvement initiatives.19 The Center for Medicare and Medicaid Services plans to utilize patient safety indicators as part of evidence-based conditions by which to adjust payment to hospitals.20
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Delirium is often considered as a less serious event than other major postoperative complications. An impetus for this study was to examine whether delirium should be considered on a par with other major life-altering or threatening postoperative complications in its own right. Other postoperative complications are risk factors for delirium, and delirium and complications can co-exist. However, the inter-relationship of delirium and other postoperative complications on the occurrence of adverse outcomes following elective noncardiac surgery has not been well-examined. Specific aims were to evaluate the association of major postoperative complications and delirium with adverse outcomes (prolonged LOS, institutional discharge, and 30-day readmission) and to examine the combined effect of postoperative complications and delirium on adverse outcomes. For the present study, delirium was not counted among the major postoperative complications, but considered separately. Our á priori hypotheses were that major complications and delirium would be separately and independently associated with adverse outcomes, and that the highest risk of adverse outcomes would be seen in the presence of both delirium and other complications.
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Study Population
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The Successful Aging after Elective Surgery (SAGES) study is a prospective cohort study of older adults undergoing major elective surgery. The study design and methods have been described in detail previously.21 In brief, eligible participants were age 70 years and older, English speaking, and scheduled to undergo elective surgery at one of two affiliated academic medical centers with an anticipated LOS of at least 3 days. Eligible surgical procedures with moderate to high risk of incident delirium included total hip or knee replacement, lumbar, cervical, or sacral laminectomy, lower extremity arterial bypass surgery, open abdominal aortic aneurysm repair, and open or laparoscopic colectomy. Exclusion criteria included evidence of dementia, active delirium or hospitalization within 3-months, terminal condition, legal blindness or severe deafness, history of schizophrenia or psychosis, and history of alcohol abuse or withdrawal. A total of 566 patients met all eligibility criteria and were enrolled between June 18, 2010 and August 8, 2013. Written informed consent for study participation was obtained from all participants according to procedures approved by the institutional review boards of Beth Israel Deaconess Medical Center and Brigham and Women’s Hospital, the two study hospitals, and Hebrew SeniorLife, the study coordinating center, all located in Boston, Massachusetts.
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Assessment of Major Postoperative Complications
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Major postoperative complications, other than delirium, were defined as occurring during the hospital stay following the index surgery, and were obtained through detailed chart review conducted by trained physicians. An expert panel of three geriatricians (SKI, EM, LJG) and one surgeon (ZC), blinded to delirium status and all study outcomes, adjudicated the presence and severity of all complications. Complications were considered major when they met or exceeded Accordion Severity Grade 2,22 and were defined as life-threatening (e.g., high mortality) or life-altering (e.g., stroke with neurologic sequelae) by the expert panel. The expert panel excluded urinary tract infection, deep vein thrombosis without pulmonary embolism, and anemia with or without blood transfusion, since these were not considered to be life-altering or threatening. Serious, complications related to these exclusions (e.g., sepsis, pulmonary embolism, unplanned return to surgery) were included. All complications were reviewed by at least three of the four adjudicators; the surgeon reviewed all cases. To achieve consensus, agreement was required by at least two of the three final adjudicators. The final set of major complications included in the analysis is shown in Table 1. Delirium Diagnosis
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Delirium assessment was performed daily beginning the day after surgery by trained staff using the Confusion Assessment Method (CAM), augmented with validated chart review method.23,24 The CAM has been validated in multiple settings and is a widely used, standardized method for identification of delirium with high sensitivity of 94% (95% confidence interval [95% CI] 91–97%), high specificity of 89% (95% CI, 85–94%), and high inter-rater reliability (kappa=0.70–1.00).24,25 The CAM algorithm requires the presence of acute change or fluctuating course of mental status symptoms, inattention, and either disorganized thinking or an altered level of consciousness to fulfill criteria for delirium. The CAM was rated based on information from participant interviews, including a brief cognitive screen,21 the Delirium Symptom Interview26, and reports from family members or nurses. Findings were adjudicated by a geriatrician and a neuropsychologist, both with extensive training information reported from family members or nurses. For the validated chart review approach, abstractors searched all sections of the chart, and coded as “yes” if any key terms or descriptors of delirium in delirium assessment.23,27 The combination of the CAM with validated chart review has been used in our previous studies.27 Study Outcomes
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Adverse outcomes used in this study were those associated with high resource utilization, including prolonged LOS, institutional discharge, and readmission defined at 30 days. LOS was obtained from chart review. A cutoff of greater than 5 days, greater than the mean of 5.2 days in our sample, was used to indicate a prolonged LOS. Institutional discharge included any discharge to a nursing home, sub-acute or acute rehabilitation facility, and was obtained from the discharge note in the medical records. Readmission within 30 days to any hospital following surgery was self-reported by study participants at a follow-up interview one month following surgery. The accuracy of the self-report information on readmissions was
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verified by medical record review in a sample of 208 participants. Overall agreement on the total number of admissions was 90% (Kappa=0.79, 95% CI, 0.71–0.87) and agreement on date of the admissions was 99% (Kappa=0.78, 95% CI, 0.72–0.85), indicating substantial agreement.28 A composite variable was created indicating the presence of any (of the 3) adverse outcomes. Other Study Variables
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During the baseline assessment participants reported their age, sex, years of formal education, race, ethnicity, and marital status. Chart review was used to collect comorbidities, surgery type, anesthesia type, and American Society of Anesthesiologists (ASA) class. Comorbidity burden was calculated using the Charlson Comorbidity Index, 29 which predicts ten-year mortality by assigning points to each comorbid condition with a higher score indicating greater mortality risk. Physical function prior to admission was assessed with basic and Instrumental Activities of Daily Living (ADL and IADL) scales.30,31 Participants were considered impaired if they required help from another person with any of the activities. Statistical Analysis The baseline characteristics and rate of adverse outcomes for participants with and without delirium and major postoperative complications are reported as means and standard deviations (SD) for continuous variables and as proportions for categorical variables. The sample was analyzed in four separate groups consisting of (1) no complications, no delirium (which served as the reference group); (2) complications only; (3) delirium only; (4) both complications and delirium.
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Robust Poisson regression32 was used to estimate the relative risk (RR) and 95% CI for each adverse outcome, as well as the risk for any adverse outcome, associated with delirium and/or major postoperative complications. Models were adjusted for baseline age in years, male sex, nonwhite race, anesthesia type (general versus spinal), Charlson Comorbidity Index score,29 and type of surgery (orthopedic versus vascular or general). The population attributable risk (PAR), measuring the proportion of each clinical outcome that could potentially be reduced if either exposure (complications or delirium) was eliminated was calculated as the product of a function of the relative risk of the outcome associated with the exposure and the prevalence the exposure. All analyses were conducted using Stata MP Version13.0 (StataCorp LP, College Station, TX). Null hypotheses were tested using a twotailed alpha of 0.05.
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Results Table 1 shows the incidence and frequency of each major postoperative complication, other than delirium. Of the 47 participants with major complications, the majority had one complication (n=36, 77%), 10 had two complications, and one participant had four complications. The most common complications were unstable arrhythmias (n=23, 4% of cohort) or respiratory failure (n=11, 2% of cohort). Other surgical complications (n=8, 1% of cohort) included unplanned return to the operating room for a range of procedures such as
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umbilical hernia repair, spinal abscess incision and drainage, abdominal compartment syndrome, anastomotic leak, wound exploration, deep surgical site infections, and drainage of a pelvic abscess.
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The baseline characteristics of the 566 study participants are shown in Table 2. The mean age (±SD) was 76.7±5.2 years. Forty-two percent of participants were men and the majority were white (92%). The most frequently performed surgeries were orthopedic (81%), followed by general (13%) and vascular (6%). Our sample consisted of 116 (20%) total hip replacements, 209 (37%) total knee replacements, 113 (20%) lumbar laminectomies, 22 (4%) cervical laminectomies, 23 (4%) lower extremity bypasses, 12 (2%) open abdominal aortic aneurysm repairs, 32 (6%) open colectomies, and 39 (7%) laparoscopic colectomies. The majority of surgeries used general anesthesia (85%). Overall, this was a highly functional group with only 7% having any ADL impairment. Major complications occurred in 47 (8%) participants and delirium in 135 (24%) participants. Differences in baseline characteristics across the four study subgroups are shown in Table 2. The subsample of participants with complications only (no delirium) had the highest average age 79.2 ±6.5 years, whereas those with both a major complication and delirium had higher scores on the Charlson Comorbidity Index (2.4 ±1.9), IADL impairment (45% participants), and greater average ASA class (90% ASA Class 3). The distribution of adverse clinical outcomes overall and across the four study subgroups is shown in Table 3. Overall, the average LOS was 5.2±3.3 days, while the reference group (no complications, no delirium) had a LOS of 4.6±1.8 days. The mean LOS was highest in the subgroups with complications—either with or without delirium (13.3 ±11.4 and 7.5±3.8 days).
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There were 323 (57%) subjects discharged to an institution. The overall proportion of discharge to an institution was greater in the subgroups with delirium alone (81%) and both delirium and complications (75%) than in those with major complications alone (48%). Readmission within 30 days occurred in 12% of the total sample, with a larger number in those with both delirium and major complications (32%). Together, major complications and delirium exerted a cumulative effect on re-hospitalization.
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Adjusted risks for adverse outcomes across the 4 study subgroups are presented in Table 4. Participants with complications alone without delirium (n=27) were more likely to have a prolonged LOS (RR 2.8, 95% CI 1.9–4.0) than those with no complications or delirium, but this subgroup had no other significant association with adverse outcomes. Delirium alone (n=115) subgroup had significantly increased risks for all adverse outcomes, including nearly 2-fold increased risk of prolonged LOS (RR 1.9, 95% CI 1.4–2.7), a 50% increased risk (RR 1.5, 95% CI 1.3–1.7) of post-acute discharge and an over 2-fold increased risk (RR 2.3, 95% CI 1.4–3.7) of readmission, compared to those with no complications or delirium. The combined subgroup with both complications and delirium (n=20) had the largest increased relative risks for all adverse outcomes, including prolonged LOS (RR 3.4, 95% CI 2.3–4.8), institutional discharge (RR 1.8, 95% CI 1.4–2.5) and readmission (RR 3.0, 95% CI 1.3–6.8), compared to all other groups.
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The associations of delirium, major complications, or both are measured with the composite variable of any adverse outcome, shown in Table 5. Across all subgroups when compared to the referent group of no complications or delirium, the RR of any adverse outcome was substantially increased. Delirium exerts the strongest risk on adverse outcomes at a population level: for any adverse outcome, 5.8% (95% CI 4.7–6.8) for delirium alone vs. 0.8% (95% CI 0.0–1.5) for complications alone and 1.3% (95% CI 1.0–1.6) for both complications and delirium. A descriptive analysis among surgery subtypes, Appendix A, showed no difference in delirium incidence or any adverse outcome. There was a difference noted in postoperative complications, and individual adverse events. A sensitivity analysis did not demonstrate any statistically significant difference in relative risks of adverse outcomes with and without adjustment for orthopedic surgery.
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Discussion
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This study investigated the rates of incident major complications and delirium following major elective surgery in older adults. It is unique in examining their separate contributions to adverse outcomes and their inter-relationship in contributing to these outcomes. Major complications alone contributed significantly only to prolonged LOS; while, delirium alone contributed significantly to all adverse outcomes (LOS, institutional discharge, and readmission). When delirium and other major complications occur together, the impact on adverse outcomes is the greatest, but this occurred relatively infrequently (20/566, 3.5%). Delirium is not consistently considered a major postoperative complication.4,8,33 However, given its prevalence and clinical impact, delirium should be considered a leading postoperative complication for predicting adverse hospital outcomes. At the population level, delirium alone exerts the greatest impact with approximately 1 in 17 patients in our study experiencing an adverse outcome attributable to delirium.
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Rates of major complications following elective surgery in this cohort were 8% with no observed in-hospital mortality. These rates were lower than some previously published rates, which range from 10%–25% following non-cardiac surgeries. One explanation for the difference is the wide range of definitions used within the literature to define postoperative complications 4,5,8,18,33,34 differences in type of surgery, and varying populations. Additionally, we evaluated delirium rates separately while some prior studies 4,5,7 include delirium as a surgical complication. In our cohort, participants who developed major complications had longer LOS, but were not found to be at increased risk for discharge to a post-acute discharge or readmission. It is possible that the LOS related to the occurrence of a complication may have allowed sufficient recovery for the participants to be safely discharged home. Delirium occurred more frequently than all other major complications combined in our surgical population (24% vs. 8%). Our observed rate of delirium was comparable to other rates published in the literature for elective non-cardiac surgeries, which range from 9.0% to 29.1%14 Delirium was associated with prolonged LOS, an increased risk of institutional
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discharge and readmission and consistent with prior studies which have demonstrated that delirium is independently associated with poor post-operative outcomes.35 The largest risk of adverse outcomes occurred in the presence of both delirium and postoperative complications. Together postoperative complications and delirium resulted in longer LOS, increased risk for post-acute discharge and readmission than the presence of either complications or delirium alone. These results suggest that it is important to manage delirium and major postoperative complications simultaneously to reduce the risks posed by both conditions. Efforts should be implemented in those at high risk of delirium or complications following elective non-cardiac surgery. Preventive strategies such as the Hospital Elder Life Program, proactive geriatric consultation and co-management services have been shown to be effective to reduce delirium, ideally when implemented before and continued after surgery.36–40
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Delirium following surgery impacts hospitals, since failure to prevent delirium can contribute to prolonged LOS, readmission rates, increased facility discharges, and ultimately, high resource utilization. Such utilization is increasingly being paid for by hospitals through bundled and global payment systems. The best way to avoid these penalties is through improvements in delirium prevention and management. This can also improve the value of care that is provided to older adults, who are increasingly represented in the evolving demographics of acute care.
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There are a number of noteworthy strengths to our study which include that the large, prospectively collected and clinically rich dataset; delirium assessment using state of the art methods; careful maintenance of blinded outcome assessment with respect to major complications and adverse hospital outcomes; chart reviews by physician experts; rigorous adjudication process of major complications by an expert panel; and a low rate of missing data. Our study was limited in that it was performed at two hospitals and included a highly educated, mostly white sample, with a low complication rate—thus, while internal validity is not impacted, generalizability may be limited. Findings will need to be replicated in other settings with more diverse samples. Unfortunately, we did not collect data on management of complications among subgroups; thus we could not evaluate whether differences in recognition and treatment of complications may have influenced the findings. Furthermore, there were a low number of complications and it was not always possible to establish the temporal relationship between the development of the complication and delirium; therefore, a causal relationship between delirium and complications could not be examined.
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In conclusion, delirium was associated with increased rates of all adverse outcomes, while major postoperative complications were associated with prolonged LOS. The highest risk of all adverse outcomes was seen in the presence of both delirium and postoperative complications. Given its high prevalence and negative impact, delirium should be considered as the leading postoperative complication contributing to adverse outcomes.
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Acknowledgments The authors thank the patients, families, nurses, physicians, and research staff participated in the SAGES study. The paper is dedicated to the memory of Joshua Bryan Inouye Helfand and Dr. Mitsuo Inouye. Grant Funding: Supported by Grants No. P01AG031720 (SKI), R01AG044518 (SKI), R03AG045633 (SKI) and K07AG041835 (SKI) from the National Institute on Aging. Dr. Gleason is supported by a HRSA training grant, D01HP08794 and a John A. Hartford Foundation Center of Excellence Award. Dr. Saczynski’s time was supported in part by Grant No. K01AG033643 from the National Institute on Aging. Dr. Marcantonio’s time was supported in part by Grant No. K24AG035075 from the National Institute on Aging. Dr. Inouye holds the Milton and Shirley F. Levy Family Chair. The funding sources had no role in the design, conduct, or reporting of this study.
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36. Chen CC, Chen CN, Lai IR, Huang GH, Saczynski JS, Inouye SK. Effects of a modified Hospital Elder Life Program on frailty in individuals undergoing major elective abdominal surgery. Journal of the American Geriatrics Society. 2014; 62(2):261–268. [PubMed: 24437990] 37. Chen CC, Saczynski J, Inouye SK. The modified Hospital Elder Life Program: adapting a complex intervention for feasibility and scalability in a surgical setting. Journal of gerontological nursing. 2014; 40(5):16–22. [PubMed: 24443887] 38. Inouye SK, Baker DI, Fugal P, Bradley EH. Dissemination of the hospital elder life program: implementation, adaptation, and successes. Journal of the American Geriatrics Society. 2006; 54(10):1492–1499. [PubMed: 17038065] 39. Marcantonio ER, Flacker JM, Wright RJ, Resnick NM. Reducing delirium after hip fracture: a randomized trial. Journal of the American Geriatrics Society. 2001; 49(5):516–522. [PubMed: 11380742] 40. Friedman SM, Mendelson DA, Bingham KW, Kates SL. Impact of a comanaged Geriatric Fracture Center on short-term hip fracture outcomes. Archives of internal medicine. 2009; 169(18):1712– 1717. [PubMed: 19822829]
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Appendix A: Baseline Characteristics Stratified by Surgery Type Overall (N=566)
Orthopedic (N=460)
Vascular (N=35)
General (N=71)
P-value
Age- mean years
77
77
77
76
0.498
Male Sex, n (%)
Characteristic
236 (42)
185 (40)
24 (69)
27 (38)
0.004
Low Education, n (%)
24 (4)
18 (4)
4 (11)
2 (3)
0.085
Non-White or Hispanic, n (%)
43 (8)
38 (8)
3 (9)
2 (3)
0.266
231 (41)
194 (42)
9 (26)
28 (39)
0.156
Charlson Comorbidity Index- mean
1
1
2
2
0.000
Charlson Score ≥2, n (%)
166 (29)
109 (24)
22 (63)
35 (49)
0.000
Any ADL Impairment, n (%)
42 (7)
38 (8)
3 (9)
1 (1)
0.118
Any IADL Impairment, n (%)
157 (28)
138 (30)
11 (31)
8 (11)
0.004
Unmarried, n (%)
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Anesthesia Type, n (%)
0.000
General
479 (85)
375 (82)
33 (94)
71 (100)
Spinal
78 (14)
77 (17)
1 (3)
0 (0)
4 (1)
3 (1)
1 (3)
0 (0)
1
2 (0)
1 (0)
0 (0)
1 (1)
2
207 (37)
182 (40)
4 (11)
21 (30)
3
352 (62)
275 (60)
30 (86)
47 (66)
Both ASA Class
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4
0.003
5 (1)
2 (0)
1 (3)
2 (3)
LOS > 5 Days, n (%)
144 (25)
84 (18)
22 (63)
38 (54)
0.000
Institutional Discharge, n (%)
323 (57)
293 (64)
14 (40)
16 (23)
0.000
30-Day Readmission, n (%)
67 (12)
47 (10)
7 (21)
13 (18)
0.049
Any Adverse Outcome, n (%)
399 (70)
329 (72)
27 (77)
43 (61)
0.114
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Characteristic
Overall (N=566)
Orthopedic (N=460)
Vascular (N=35)
General (N=71)
P-value
Postoperative Delirium, n (%)
135 (24)
106 (23)
11 (31)
18 (25)
0.507
47 (8)
29 (6)
9 (26)
9 (13)
0.000
Major Postoperative Complication, n (%) a
ADL= activities of daily living;
b
IADL= Instrumental activities of daily living; a,b Impairment defined as any impairment in one or more basic (or instrumental) activity of daily living c ASA= American Society of Anesthesiologists physical status classification system
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Table 1
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Rates of Major Postoperative Complications Major Complications, excluding delirium
n (%)
Unstable Arrhythmiaa
23 (4)
New Heart Blockb
1 (0)
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NSTEMI
4 (1)
Respiratory Failurec
11 (2)
Pulmonary Embolism
5 (1)
Pneumonia
2 (0)
Sepsis
2 (0)
New Renal Failured
2 (0)
Stroke
2 (0)
Surgical Complicationse
8 (1)
Any Complication
47(8)
a
New atrial fibrillation/flutter or other supraventricular tachycardia requiring treatment
b
Requiring Pacemaker
c
Includes pulmonary edema, respiratory distress, re-intubation, unable to wean from ventilator
d
Requiring dialysis
e Surgical wound infection, surgery-specific complications, unplanned return to the OR
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JAMA Surg. Author manuscript; available in PMC 2016 December 01. 71 (13)
78 (14) 4 (1)
Spinal
Both
352 (62) 5 (1)
2
3
4
SD = standard deviation;
2 (0) 207 (37)
1
ASA Classd, n (%)
479 (85)
General
Anesthesia Type, n (%)
b,c Impairment defined as any impairment in one or more basic (or instrumental) activity of daily living
c IADL= Instrumental activities of daily living;
2 (0.5)
234 (57.9)
166 (41.1)
2 (0.5)
2 (0)
63 (16)
336 (83)
48 (12)
35 (6)
General
19 (5)
460 (81)
Vascular
337 (83)
100 (25)
27 (7)
101 (25)
0.9 ± 1.2
165 (41)
29 (7)
17 (4)
168 (42)
76.3 ± 5.1
Orthopedic
ADL= activities of daily living;
b
a
157 (28)
Any IADL impairmentc, n (%)
Surgery type, n (%)
42 (7)
Any ADL impairmentb, n (%)
167 (30)
1.0 ± 1.3
Charlson Index- mean ± SDa
Score≥2, n (%)
43 (8) 231 (41)
24 (4)
Low education, n (%)
Unmarried, n (%)
236 (42)
Male sex, n (%)
Non-white or Hispanic, n (%)
76.7 ± 5.2
Age- mean years ± SDa
Full Sample (n=566)
No Complications or Delirium (n=404)
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Characteristic
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Characteristics of Study Population
2 (7.4)
17 (63.0)
8 (29.6)
0 (0.0)
1 (4)
2 (7)
23 (85)
5 (19)
5 (19)
17 (63)
8 (30)
3 (11)
8 (30)
1.5 ± 1.8
10 (37)
1 (4)
0 (0)
15 (56)
79.2 ± 6.5
Complications Only (n=27)
1 (0.9)
83 (72.2)
31 (27.0)
0 (0.0)
1 (1)
12 (10)
101 (88)
14 (12)
7 (6)
94 (82)
40 (35)
11 (10)
46 (40)
1.1 ± 1.2
53 (46)
13 (11)
5 (4)
42 (37)
77.7 ± 5.0
Delirium Only (n=115)
0 (0.0)
18 (90)
2 (10)
0 (0.0)
0 (0)
1 (5)
19 (95)
4 (20)
4 (20)
12 (60)
9 (45)
1 (5)
12 (60)
2.4 ± 1.9
3 (15)
0 (0)
2 (10)
11 (55)
76.1 ± 5.0
Both Complications and Delirium (n=20)
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Table 2 Gleason et al. Page 14
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d
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ASA= American Society of Anesthesiologists physical status classification system
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Author Manuscript 4.6 ± 1.8 7.5 ± 3.8 5.5 ± 2.1 13.3 ± 11.4
No Complication and no delirium (n=404)
Complications only (n=27)
Delirium only (n=115)
Both complications and delirium (n=20)
SD= Standard Deviation
a
5.2 ± 3.3
Full Sample (n=566)
mean days ± SDa
18 (90)
40 (35)
17 (63)
69 (17)
144 (25)
n (%) >5 days
Length of Stay
15 (75)
93 (81)
13 (48)
202 (50)
323 (57)
Discharge, n (%)
Institutional Discharge
6 (30)
22 (19)
5 (19)
34 (8)
67 (12)
30-Day Readmission, n (%)
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Adverse Outcomes by Complication and Delirium Status
20 (100)
105 (91)
22 (81)
252 (62)
399 (70)
Any Adverse Outcome, n (%)
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Table 3 Gleason et al. Page 16
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Referent
1.8 (1.4, 2.5)
1.5 (1.3, 1.7)
1.0 (0.7, 1.5)
3.0 (1.3, 6.8)
2.3 (1.4, 3.7)
1.6 (0.6, 4.2)
Adjusted RR (95% CI)
30-Day Readmission
Adjusted for age, sex, race, Charlson Index, surgery type (orthopedic vs. all else), and anesthesia type (general vs. spinal).
a
Relative risks (RR) are calculated with a generalized linear model, Poisson error term, log-link and robust error varianc
1.9 (1.4, 2.7)
Both complications and delirium (n=20)
2.8 (1.9, 4.0)
Adjusted RR (95% CI)
Adjusted RR (95% CI)
Delirium only (n=115)
Complications only (n=27)
No Complication and no delirium (n=404)
Institutional Discharge
Length of stay >5 days
Association of Adverse Hospital Outcomes by Complication and Delirium Statusa
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Table 4 Gleason et al. Page 17
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Author Manuscript 20 (100)
Delirium only (n=115)
Both complications and delirium (n=20)
1.6 (1.4, 1.8)
1.4 (1.3, 1.5)
1.2 (1.0, 1.6)
1.3 (1.0, 1.6)
5.8 (4.7, 6.8)
0.8 (0.0, 1.5)
PAR % (95% CI)b
Referent
Adjusted RR (95% CI)
Adjusted for age, sex, race, Charlson Index, surgery type (orthopedic vs. all else), and anesthesia type (general vs. spinal).
Population attributable (PAR) risk percentage is the product of a function of the relative risk of the outcome associated with the exposure and the prevalence of adverse outcome. PAR is the difference in rate of a condition between an exposed population and an unexposed population.
b
a
Relative risks (RR) are calculated with a generalized linear model, poisson error term, log-link and robust error variance
22 (81) 105 (91)
Complications only (n=27)
252 (62)
No Complications or delirium (n=404)
n (%)
Any Adverse Outcome
Association of Any Adverse Hospital Outcomes by Complication and Delirium Statusa
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Table 5 Gleason et al. Page 18
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JAMA Surg. Author manuscript; available in PMC 2016 December 01. Published in final edited form as: JAMA Surg. 2015 December 1; 150(12): 1134–1140. doi:10.1001/jamasurg.2015.2606.
Effect of Delirium and Other Major Complications After Elective Surgery in Older Adults Lauren J. Gleason, MD1,2, Eva M. Schmitt, PhD2, Cyrus M. Kosar, MA2, Patricia Tabloski, PhD3, Jane S. Saczynski, PhD4, Thomas Robinson, MD5, Zara Cooper, MD6, Selwyn O. Rogers Jr., MD, MPH7, Richard N. Jones, ScD8, Edward R. Marcantonio, MD, SM1,*, and Sharon K. Inouye, MD, MPH1,2,*
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1Department
of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School,
Boston, MA 2Aging
Brain Center, Institute for Aging Research, Hebrew SeniorLife
3William
F. Connell School of Nursing, Boston College, Boston, MA
4Division
of Geriatric Medicine and Meyers Primary Care Institute, University of Massachusetts Medical School, Worcester, MA
5Department
of Surgery, University of Colorado
6Department
of Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
7University
of Texas Medical Branch at Galveston, Galveston, Texas
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8Departments
of Psychiatry and Human Behavior, Brown University Warren Alpert Medical School, Providence RI
Abstract Importance—Major postoperative complications and delirium contribute independently to adverse outcomes and high resource utilization in patients undergoing major surgery; however, their inter-relationship is not well-examined. Objective—To evaluate the association of major postoperative complications and delirium, alone and in combination, with adverse outcomes after surgery. Design—Prospective cohort study.
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Setting—Two large academic medical centers. Participants—Patients without recognized dementia or history of delirium, age 70 and older who underwent elective major orthopedic, vascular, and abdominal surgeries with a minimum 3day hospitalization.
Corresponding Author: Sharon K. Inouye, MD, MPH, Aging Brain Center, Institute for Aging Research, Hebrew SeniorLife; 1200 Centre Street; Boston, MA 02131 USA, [email protected], Phone: 617-971-5390; Fax: 617-971-5309. *Drs. Marcantonio and Inouye contributed equally as co-senior authors. Drs. Gleason and Inouye had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
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Main Outcome and Measures—Major postoperative complications, defined as life altering or threatening events (Accordion Severity ≥ grade 2), were identified by expert panel adjudication. Delirium was measured daily with the Confusion Assessment Method and a validated chart review method. Four subgroups were analyzed: (1) no complications, no delirium; (2) complications alone; (3) delirium alone; and (4) both complications and delirium. Adverse outcomes included length of stay (LOS) > 5 days, institutional discharge, and rehospitalization within 30 days of discharge.
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Results—Of 566 participants, mean age (±SD) was 76.7± 5.2 years, 42% male and 92% white. Forty-seven (8%) developed major complications, and 135 (24%) developed delirium. When compared to no complications, no delirium as the reference group, major complications alone contributed only to prolonged LOS (RR 2.8, 95% CI 1.9–4.0); by contrast, delirium alone significantly increased all adverse outcomes, including prolonged LOS (RR 1.9, 95% CI 1.4–2.7), institutional discharge (RR 1.5, 95% CI 1.3–1.7), and 30-day readmission (RR 2.3, 95% CI 1.4– 3.7). The subgroup with both complications and delirium had the highest rates of all adverse outcomes, including prolonged LOS (RR 3.4, 95% CI 2.3–4.8), institutional discharge (RR 1.8, 95% CI 1.4–2.5) and 30-day readmission (RR 3.0, 95% CI 1.3–6.8). Delirium exerted the highest attributable risk at a population level (5.8%, 95% CI 4.7–6.8) compared with all other adverse events (prolonged LOS, institutional discharge, or readmission). Conclusions and Relevance—Major postoperative complications and delirium are separately associated with adverse events and demonstrate a strong combined effect. Delirium occurs more frequently, and has greater impact at the population level than other major complications. Keywords Delirium; postoperative complications; Confusion Assessment Method; adverse surgical outcomes
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Introduction Thirty-six percent of inpatient operations were performed in patients ≥65 years old.1 The number of patients is projected to increase as the population ages.1,2 Understanding the risks for adverse outcomes in the aging surgical population is essential to implement programs with the potential to decrease morbidity, mortality, costs, and safety. Postoperative complications increase with advancing age.3,4 These complications, occurring in 10–25% older persons,3–7 can lead to adverse outcomes such as disability, loss of independence, diminished quality of life, high health care costs, and increased mortality.8 Physiologic changes across organ systems, cardiovascular, neurological, and pulmonary systems, contribute to the increasing risk of postoperative complications with advancing age.6,8
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Postoperative delirium as the leading complication of major surgery in older persons with adverse consequences has been well documented across many studies.9–12 It is associated with higher in-hospital and 6-month mortality, functional decline, greater rates of institutional discharge, longer lengths of stay (LOS), increased use of hospital resources and higher healthcare costs.9–14 Delirium rates following surgery range from 5%–50%.12,14,15 Its impact on annual health care costs is estimated at over $182 billion per year in the U.S. (2011 USD),16 and thus, has assumed increasing attention as a public health and patient
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safety priority.17 Since complications and delirium are often preventable, they can be tracked and monitored as markers of quality of care.18 Such markers have become a major focus of the National Quality Forum and emerged at the forefront of many quality improvement initiatives.19 The Center for Medicare and Medicaid Services plans to utilize patient safety indicators as part of evidence-based conditions by which to adjust payment to hospitals.20
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Delirium is often considered as a less serious event than other major postoperative complications. An impetus for this study was to examine whether delirium should be considered on a par with other major life-altering or threatening postoperative complications in its own right. Other postoperative complications are risk factors for delirium, and delirium and complications can co-exist. However, the inter-relationship of delirium and other postoperative complications on the occurrence of adverse outcomes following elective noncardiac surgery has not been well-examined. Specific aims were to evaluate the association of major postoperative complications and delirium with adverse outcomes (prolonged LOS, institutional discharge, and 30-day readmission) and to examine the combined effect of postoperative complications and delirium on adverse outcomes. For the present study, delirium was not counted among the major postoperative complications, but considered separately. Our á priori hypotheses were that major complications and delirium would be separately and independently associated with adverse outcomes, and that the highest risk of adverse outcomes would be seen in the presence of both delirium and other complications.
Methods Author Manuscript
Study Population
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The Successful Aging after Elective Surgery (SAGES) study is a prospective cohort study of older adults undergoing major elective surgery. The study design and methods have been described in detail previously.21 In brief, eligible participants were age 70 years and older, English speaking, and scheduled to undergo elective surgery at one of two affiliated academic medical centers with an anticipated LOS of at least 3 days. Eligible surgical procedures with moderate to high risk of incident delirium included total hip or knee replacement, lumbar, cervical, or sacral laminectomy, lower extremity arterial bypass surgery, open abdominal aortic aneurysm repair, and open or laparoscopic colectomy. Exclusion criteria included evidence of dementia, active delirium or hospitalization within 3-months, terminal condition, legal blindness or severe deafness, history of schizophrenia or psychosis, and history of alcohol abuse or withdrawal. A total of 566 patients met all eligibility criteria and were enrolled between June 18, 2010 and August 8, 2013. Written informed consent for study participation was obtained from all participants according to procedures approved by the institutional review boards of Beth Israel Deaconess Medical Center and Brigham and Women’s Hospital, the two study hospitals, and Hebrew SeniorLife, the study coordinating center, all located in Boston, Massachusetts.
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Assessment of Major Postoperative Complications
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Major postoperative complications, other than delirium, were defined as occurring during the hospital stay following the index surgery, and were obtained through detailed chart review conducted by trained physicians. An expert panel of three geriatricians (SKI, EM, LJG) and one surgeon (ZC), blinded to delirium status and all study outcomes, adjudicated the presence and severity of all complications. Complications were considered major when they met or exceeded Accordion Severity Grade 2,22 and were defined as life-threatening (e.g., high mortality) or life-altering (e.g., stroke with neurologic sequelae) by the expert panel. The expert panel excluded urinary tract infection, deep vein thrombosis without pulmonary embolism, and anemia with or without blood transfusion, since these were not considered to be life-altering or threatening. Serious, complications related to these exclusions (e.g., sepsis, pulmonary embolism, unplanned return to surgery) were included. All complications were reviewed by at least three of the four adjudicators; the surgeon reviewed all cases. To achieve consensus, agreement was required by at least two of the three final adjudicators. The final set of major complications included in the analysis is shown in Table 1. Delirium Diagnosis
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Delirium assessment was performed daily beginning the day after surgery by trained staff using the Confusion Assessment Method (CAM), augmented with validated chart review method.23,24 The CAM has been validated in multiple settings and is a widely used, standardized method for identification of delirium with high sensitivity of 94% (95% confidence interval [95% CI] 91–97%), high specificity of 89% (95% CI, 85–94%), and high inter-rater reliability (kappa=0.70–1.00).24,25 The CAM algorithm requires the presence of acute change or fluctuating course of mental status symptoms, inattention, and either disorganized thinking or an altered level of consciousness to fulfill criteria for delirium. The CAM was rated based on information from participant interviews, including a brief cognitive screen,21 the Delirium Symptom Interview26, and reports from family members or nurses. Findings were adjudicated by a geriatrician and a neuropsychologist, both with extensive training information reported from family members or nurses. For the validated chart review approach, abstractors searched all sections of the chart, and coded as “yes” if any key terms or descriptors of delirium in delirium assessment.23,27 The combination of the CAM with validated chart review has been used in our previous studies.27 Study Outcomes
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Adverse outcomes used in this study were those associated with high resource utilization, including prolonged LOS, institutional discharge, and readmission defined at 30 days. LOS was obtained from chart review. A cutoff of greater than 5 days, greater than the mean of 5.2 days in our sample, was used to indicate a prolonged LOS. Institutional discharge included any discharge to a nursing home, sub-acute or acute rehabilitation facility, and was obtained from the discharge note in the medical records. Readmission within 30 days to any hospital following surgery was self-reported by study participants at a follow-up interview one month following surgery. The accuracy of the self-report information on readmissions was
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verified by medical record review in a sample of 208 participants. Overall agreement on the total number of admissions was 90% (Kappa=0.79, 95% CI, 0.71–0.87) and agreement on date of the admissions was 99% (Kappa=0.78, 95% CI, 0.72–0.85), indicating substantial agreement.28 A composite variable was created indicating the presence of any (of the 3) adverse outcomes. Other Study Variables
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During the baseline assessment participants reported their age, sex, years of formal education, race, ethnicity, and marital status. Chart review was used to collect comorbidities, surgery type, anesthesia type, and American Society of Anesthesiologists (ASA) class. Comorbidity burden was calculated using the Charlson Comorbidity Index, 29 which predicts ten-year mortality by assigning points to each comorbid condition with a higher score indicating greater mortality risk. Physical function prior to admission was assessed with basic and Instrumental Activities of Daily Living (ADL and IADL) scales.30,31 Participants were considered impaired if they required help from another person with any of the activities. Statistical Analysis The baseline characteristics and rate of adverse outcomes for participants with and without delirium and major postoperative complications are reported as means and standard deviations (SD) for continuous variables and as proportions for categorical variables. The sample was analyzed in four separate groups consisting of (1) no complications, no delirium (which served as the reference group); (2) complications only; (3) delirium only; (4) both complications and delirium.
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Robust Poisson regression32 was used to estimate the relative risk (RR) and 95% CI for each adverse outcome, as well as the risk for any adverse outcome, associated with delirium and/or major postoperative complications. Models were adjusted for baseline age in years, male sex, nonwhite race, anesthesia type (general versus spinal), Charlson Comorbidity Index score,29 and type of surgery (orthopedic versus vascular or general). The population attributable risk (PAR), measuring the proportion of each clinical outcome that could potentially be reduced if either exposure (complications or delirium) was eliminated was calculated as the product of a function of the relative risk of the outcome associated with the exposure and the prevalence the exposure. All analyses were conducted using Stata MP Version13.0 (StataCorp LP, College Station, TX). Null hypotheses were tested using a twotailed alpha of 0.05.
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Results Table 1 shows the incidence and frequency of each major postoperative complication, other than delirium. Of the 47 participants with major complications, the majority had one complication (n=36, 77%), 10 had two complications, and one participant had four complications. The most common complications were unstable arrhythmias (n=23, 4% of cohort) or respiratory failure (n=11, 2% of cohort). Other surgical complications (n=8, 1% of cohort) included unplanned return to the operating room for a range of procedures such as
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umbilical hernia repair, spinal abscess incision and drainage, abdominal compartment syndrome, anastomotic leak, wound exploration, deep surgical site infections, and drainage of a pelvic abscess.
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The baseline characteristics of the 566 study participants are shown in Table 2. The mean age (±SD) was 76.7±5.2 years. Forty-two percent of participants were men and the majority were white (92%). The most frequently performed surgeries were orthopedic (81%), followed by general (13%) and vascular (6%). Our sample consisted of 116 (20%) total hip replacements, 209 (37%) total knee replacements, 113 (20%) lumbar laminectomies, 22 (4%) cervical laminectomies, 23 (4%) lower extremity bypasses, 12 (2%) open abdominal aortic aneurysm repairs, 32 (6%) open colectomies, and 39 (7%) laparoscopic colectomies. The majority of surgeries used general anesthesia (85%). Overall, this was a highly functional group with only 7% having any ADL impairment. Major complications occurred in 47 (8%) participants and delirium in 135 (24%) participants. Differences in baseline characteristics across the four study subgroups are shown in Table 2. The subsample of participants with complications only (no delirium) had the highest average age 79.2 ±6.5 years, whereas those with both a major complication and delirium had higher scores on the Charlson Comorbidity Index (2.4 ±1.9), IADL impairment (45% participants), and greater average ASA class (90% ASA Class 3). The distribution of adverse clinical outcomes overall and across the four study subgroups is shown in Table 3. Overall, the average LOS was 5.2±3.3 days, while the reference group (no complications, no delirium) had a LOS of 4.6±1.8 days. The mean LOS was highest in the subgroups with complications—either with or without delirium (13.3 ±11.4 and 7.5±3.8 days).
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There were 323 (57%) subjects discharged to an institution. The overall proportion of discharge to an institution was greater in the subgroups with delirium alone (81%) and both delirium and complications (75%) than in those with major complications alone (48%). Readmission within 30 days occurred in 12% of the total sample, with a larger number in those with both delirium and major complications (32%). Together, major complications and delirium exerted a cumulative effect on re-hospitalization.
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Adjusted risks for adverse outcomes across the 4 study subgroups are presented in Table 4. Participants with complications alone without delirium (n=27) were more likely to have a prolonged LOS (RR 2.8, 95% CI 1.9–4.0) than those with no complications or delirium, but this subgroup had no other significant association with adverse outcomes. Delirium alone (n=115) subgroup had significantly increased risks for all adverse outcomes, including nearly 2-fold increased risk of prolonged LOS (RR 1.9, 95% CI 1.4–2.7), a 50% increased risk (RR 1.5, 95% CI 1.3–1.7) of post-acute discharge and an over 2-fold increased risk (RR 2.3, 95% CI 1.4–3.7) of readmission, compared to those with no complications or delirium. The combined subgroup with both complications and delirium (n=20) had the largest increased relative risks for all adverse outcomes, including prolonged LOS (RR 3.4, 95% CI 2.3–4.8), institutional discharge (RR 1.8, 95% CI 1.4–2.5) and readmission (RR 3.0, 95% CI 1.3–6.8), compared to all other groups.
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The associations of delirium, major complications, or both are measured with the composite variable of any adverse outcome, shown in Table 5. Across all subgroups when compared to the referent group of no complications or delirium, the RR of any adverse outcome was substantially increased. Delirium exerts the strongest risk on adverse outcomes at a population level: for any adverse outcome, 5.8% (95% CI 4.7–6.8) for delirium alone vs. 0.8% (95% CI 0.0–1.5) for complications alone and 1.3% (95% CI 1.0–1.6) for both complications and delirium. A descriptive analysis among surgery subtypes, Appendix A, showed no difference in delirium incidence or any adverse outcome. There was a difference noted in postoperative complications, and individual adverse events. A sensitivity analysis did not demonstrate any statistically significant difference in relative risks of adverse outcomes with and without adjustment for orthopedic surgery.
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Discussion
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This study investigated the rates of incident major complications and delirium following major elective surgery in older adults. It is unique in examining their separate contributions to adverse outcomes and their inter-relationship in contributing to these outcomes. Major complications alone contributed significantly only to prolonged LOS; while, delirium alone contributed significantly to all adverse outcomes (LOS, institutional discharge, and readmission). When delirium and other major complications occur together, the impact on adverse outcomes is the greatest, but this occurred relatively infrequently (20/566, 3.5%). Delirium is not consistently considered a major postoperative complication.4,8,33 However, given its prevalence and clinical impact, delirium should be considered a leading postoperative complication for predicting adverse hospital outcomes. At the population level, delirium alone exerts the greatest impact with approximately 1 in 17 patients in our study experiencing an adverse outcome attributable to delirium.
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Rates of major complications following elective surgery in this cohort were 8% with no observed in-hospital mortality. These rates were lower than some previously published rates, which range from 10%–25% following non-cardiac surgeries. One explanation for the difference is the wide range of definitions used within the literature to define postoperative complications 4,5,8,18,33,34 differences in type of surgery, and varying populations. Additionally, we evaluated delirium rates separately while some prior studies 4,5,7 include delirium as a surgical complication. In our cohort, participants who developed major complications had longer LOS, but were not found to be at increased risk for discharge to a post-acute discharge or readmission. It is possible that the LOS related to the occurrence of a complication may have allowed sufficient recovery for the participants to be safely discharged home. Delirium occurred more frequently than all other major complications combined in our surgical population (24% vs. 8%). Our observed rate of delirium was comparable to other rates published in the literature for elective non-cardiac surgeries, which range from 9.0% to 29.1%14 Delirium was associated with prolonged LOS, an increased risk of institutional
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discharge and readmission and consistent with prior studies which have demonstrated that delirium is independently associated with poor post-operative outcomes.35 The largest risk of adverse outcomes occurred in the presence of both delirium and postoperative complications. Together postoperative complications and delirium resulted in longer LOS, increased risk for post-acute discharge and readmission than the presence of either complications or delirium alone. These results suggest that it is important to manage delirium and major postoperative complications simultaneously to reduce the risks posed by both conditions. Efforts should be implemented in those at high risk of delirium or complications following elective non-cardiac surgery. Preventive strategies such as the Hospital Elder Life Program, proactive geriatric consultation and co-management services have been shown to be effective to reduce delirium, ideally when implemented before and continued after surgery.36–40
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Delirium following surgery impacts hospitals, since failure to prevent delirium can contribute to prolonged LOS, readmission rates, increased facility discharges, and ultimately, high resource utilization. Such utilization is increasingly being paid for by hospitals through bundled and global payment systems. The best way to avoid these penalties is through improvements in delirium prevention and management. This can also improve the value of care that is provided to older adults, who are increasingly represented in the evolving demographics of acute care.
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There are a number of noteworthy strengths to our study which include that the large, prospectively collected and clinically rich dataset; delirium assessment using state of the art methods; careful maintenance of blinded outcome assessment with respect to major complications and adverse hospital outcomes; chart reviews by physician experts; rigorous adjudication process of major complications by an expert panel; and a low rate of missing data. Our study was limited in that it was performed at two hospitals and included a highly educated, mostly white sample, with a low complication rate—thus, while internal validity is not impacted, generalizability may be limited. Findings will need to be replicated in other settings with more diverse samples. Unfortunately, we did not collect data on management of complications among subgroups; thus we could not evaluate whether differences in recognition and treatment of complications may have influenced the findings. Furthermore, there were a low number of complications and it was not always possible to establish the temporal relationship between the development of the complication and delirium; therefore, a causal relationship between delirium and complications could not be examined.
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In conclusion, delirium was associated with increased rates of all adverse outcomes, while major postoperative complications were associated with prolonged LOS. The highest risk of all adverse outcomes was seen in the presence of both delirium and postoperative complications. Given its high prevalence and negative impact, delirium should be considered as the leading postoperative complication contributing to adverse outcomes.
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Acknowledgments The authors thank the patients, families, nurses, physicians, and research staff participated in the SAGES study. The paper is dedicated to the memory of Joshua Bryan Inouye Helfand and Dr. Mitsuo Inouye. Grant Funding: Supported by Grants No. P01AG031720 (SKI), R01AG044518 (SKI), R03AG045633 (SKI) and K07AG041835 (SKI) from the National Institute on Aging. Dr. Gleason is supported by a HRSA training grant, D01HP08794 and a John A. Hartford Foundation Center of Excellence Award. Dr. Saczynski’s time was supported in part by Grant No. K01AG033643 from the National Institute on Aging. Dr. Marcantonio’s time was supported in part by Grant No. K24AG035075 from the National Institute on Aging. Dr. Inouye holds the Milton and Shirley F. Levy Family Chair. The funding sources had no role in the design, conduct, or reporting of this study.
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Appendix A: Baseline Characteristics Stratified by Surgery Type Overall (N=566)
Orthopedic (N=460)
Vascular (N=35)
General (N=71)
P-value
Age- mean years
77
77
77
76
0.498
Male Sex, n (%)
Characteristic
236 (42)
185 (40)
24 (69)
27 (38)
0.004
Low Education, n (%)
24 (4)
18 (4)
4 (11)
2 (3)
0.085
Non-White or Hispanic, n (%)
43 (8)
38 (8)
3 (9)
2 (3)
0.266
231 (41)
194 (42)
9 (26)
28 (39)
0.156
Charlson Comorbidity Index- mean
1
1
2
2
0.000
Charlson Score ≥2, n (%)
166 (29)
109 (24)
22 (63)
35 (49)
0.000
Any ADL Impairment, n (%)
42 (7)
38 (8)
3 (9)
1 (1)
0.118
Any IADL Impairment, n (%)
157 (28)
138 (30)
11 (31)
8 (11)
0.004
Unmarried, n (%)
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Anesthesia Type, n (%)
0.000
General
479 (85)
375 (82)
33 (94)
71 (100)
Spinal
78 (14)
77 (17)
1 (3)
0 (0)
4 (1)
3 (1)
1 (3)
0 (0)
1
2 (0)
1 (0)
0 (0)
1 (1)
2
207 (37)
182 (40)
4 (11)
21 (30)
3
352 (62)
275 (60)
30 (86)
47 (66)
Both ASA Class
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4
0.003
5 (1)
2 (0)
1 (3)
2 (3)
LOS > 5 Days, n (%)
144 (25)
84 (18)
22 (63)
38 (54)
0.000
Institutional Discharge, n (%)
323 (57)
293 (64)
14 (40)
16 (23)
0.000
30-Day Readmission, n (%)
67 (12)
47 (10)
7 (21)
13 (18)
0.049
Any Adverse Outcome, n (%)
399 (70)
329 (72)
27 (77)
43 (61)
0.114
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Characteristic
Overall (N=566)
Orthopedic (N=460)
Vascular (N=35)
General (N=71)
P-value
Postoperative Delirium, n (%)
135 (24)
106 (23)
11 (31)
18 (25)
0.507
47 (8)
29 (6)
9 (26)
9 (13)
0.000
Major Postoperative Complication, n (%) a
ADL= activities of daily living;
b
IADL= Instrumental activities of daily living; a,b Impairment defined as any impairment in one or more basic (or instrumental) activity of daily living c ASA= American Society of Anesthesiologists physical status classification system
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Table 1
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Rates of Major Postoperative Complications Major Complications, excluding delirium
n (%)
Unstable Arrhythmiaa
23 (4)
New Heart Blockb
1 (0)
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NSTEMI
4 (1)
Respiratory Failurec
11 (2)
Pulmonary Embolism
5 (1)
Pneumonia
2 (0)
Sepsis
2 (0)
New Renal Failured
2 (0)
Stroke
2 (0)
Surgical Complicationse
8 (1)
Any Complication
47(8)
a
New atrial fibrillation/flutter or other supraventricular tachycardia requiring treatment
b
Requiring Pacemaker
c
Includes pulmonary edema, respiratory distress, re-intubation, unable to wean from ventilator
d
Requiring dialysis
e Surgical wound infection, surgery-specific complications, unplanned return to the OR
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78 (14) 4 (1)
Spinal
Both
352 (62) 5 (1)
2
3
4
SD = standard deviation;
2 (0) 207 (37)
1
ASA Classd, n (%)
479 (85)
General
Anesthesia Type, n (%)
b,c Impairment defined as any impairment in one or more basic (or instrumental) activity of daily living
c IADL= Instrumental activities of daily living;
2 (0.5)
234 (57.9)
166 (41.1)
2 (0.5)
2 (0)
63 (16)
336 (83)
48 (12)
35 (6)
General
19 (5)
460 (81)
Vascular
337 (83)
100 (25)
27 (7)
101 (25)
0.9 ± 1.2
165 (41)
29 (7)
17 (4)
168 (42)
76.3 ± 5.1
Orthopedic
ADL= activities of daily living;
b
a
157 (28)
Any IADL impairmentc, n (%)
Surgery type, n (%)
42 (7)
Any ADL impairmentb, n (%)
167 (30)
1.0 ± 1.3
Charlson Index- mean ± SDa
Score≥2, n (%)
43 (8) 231 (41)
24 (4)
Low education, n (%)
Unmarried, n (%)
236 (42)
Male sex, n (%)
Non-white or Hispanic, n (%)
76.7 ± 5.2
Age- mean years ± SDa
Full Sample (n=566)
No Complications or Delirium (n=404)
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Characteristic
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Characteristics of Study Population
2 (7.4)
17 (63.0)
8 (29.6)
0 (0.0)
1 (4)
2 (7)
23 (85)
5 (19)
5 (19)
17 (63)
8 (30)
3 (11)
8 (30)
1.5 ± 1.8
10 (37)
1 (4)
0 (0)
15 (56)
79.2 ± 6.5
Complications Only (n=27)
1 (0.9)
83 (72.2)
31 (27.0)
0 (0.0)
1 (1)
12 (10)
101 (88)
14 (12)
7 (6)
94 (82)
40 (35)
11 (10)
46 (40)
1.1 ± 1.2
53 (46)
13 (11)
5 (4)
42 (37)
77.7 ± 5.0
Delirium Only (n=115)
0 (0.0)
18 (90)
2 (10)
0 (0.0)
0 (0)
1 (5)
19 (95)
4 (20)
4 (20)
12 (60)
9 (45)
1 (5)
12 (60)
2.4 ± 1.9
3 (15)
0 (0)
2 (10)
11 (55)
76.1 ± 5.0
Both Complications and Delirium (n=20)
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d
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ASA= American Society of Anesthesiologists physical status classification system
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Author Manuscript 4.6 ± 1.8 7.5 ± 3.8 5.5 ± 2.1 13.3 ± 11.4
No Complication and no delirium (n=404)
Complications only (n=27)
Delirium only (n=115)
Both complications and delirium (n=20)
SD= Standard Deviation
a
5.2 ± 3.3
Full Sample (n=566)
mean days ± SDa
18 (90)
40 (35)
17 (63)
69 (17)
144 (25)
n (%) >5 days
Length of Stay
15 (75)
93 (81)
13 (48)
202 (50)
323 (57)
Discharge, n (%)
Institutional Discharge
6 (30)
22 (19)
5 (19)
34 (8)
67 (12)
30-Day Readmission, n (%)
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Adverse Outcomes by Complication and Delirium Status
20 (100)
105 (91)
22 (81)
252 (62)
399 (70)
Any Adverse Outcome, n (%)
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Referent
1.8 (1.4, 2.5)
1.5 (1.3, 1.7)
1.0 (0.7, 1.5)
3.0 (1.3, 6.8)
2.3 (1.4, 3.7)
1.6 (0.6, 4.2)
Adjusted RR (95% CI)
30-Day Readmission
Adjusted for age, sex, race, Charlson Index, surgery type (orthopedic vs. all else), and anesthesia type (general vs. spinal).
a
Relative risks (RR) are calculated with a generalized linear model, Poisson error term, log-link and robust error varianc
1.9 (1.4, 2.7)
Both complications and delirium (n=20)
2.8 (1.9, 4.0)
Adjusted RR (95% CI)
Adjusted RR (95% CI)
Delirium only (n=115)
Complications only (n=27)
No Complication and no delirium (n=404)
Institutional Discharge
Length of stay >5 days
Association of Adverse Hospital Outcomes by Complication and Delirium Statusa
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Delirium only (n=115)
Both complications and delirium (n=20)
1.6 (1.4, 1.8)
1.4 (1.3, 1.5)
1.2 (1.0, 1.6)
1.3 (1.0, 1.6)
5.8 (4.7, 6.8)
0.8 (0.0, 1.5)
PAR % (95% CI)b
Referent
Adjusted RR (95% CI)
Adjusted for age, sex, race, Charlson Index, surgery type (orthopedic vs. all else), and anesthesia type (general vs. spinal).
Population attributable (PAR) risk percentage is the product of a function of the relative risk of the outcome associated with the exposure and the prevalence of adverse outcome. PAR is the difference in rate of a condition between an exposed population and an unexposed population.
b
a
Relative risks (RR) are calculated with a generalized linear model, poisson error term, log-link and robust error variance
22 (81) 105 (91)
Complications only (n=27)
252 (62)
No Complications or delirium (n=404)
n (%)
Any Adverse Outcome
Association of Any Adverse Hospital Outcomes by Complication and Delirium Statusa
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Table 5 Gleason et al. Page 18
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